Neastacilla coonabooloo, King, 2003

King, R. A., 2003, Neastacilla Tattersall, 1921 redefined, with eight new species from Australia (Crustacea: Isopoda: Arcturidae), Memoirs of Museum Victoria 60 (2), pp. 371-416 : 376-380

Neastacilla coonabooloo sp. nov.

Figures 1–3

Material examined. Holotype. Australia: Vic., Crib Point , Western Port, 38º21.15'S, 145º13.36'E, 9 m, 24 Mar 1965, NMV J1036 (1 female, 6.6 mm).

Paratypes. Australia: NSW. Moes Rock , S of Jervis Bay, AM P32681 (1 female), AM P32680 (1 female). Vic. Crib Point, Western Port , 38º21.63'S, 145º15.08'E, 9 m, 23 Feb 1965, NMV J978 (1 female), NMV J979 (1 female). Western Port , 38º22.0'S, 145º32.0'E, NMV J980 (1 immature female, 1 immature male). Mallacoota , 37º34.03'S, 149º46.02'E, 5 m, 6 Apr 1989, NMV J47324 (1 immature female). Tas. Breaksea Island, Bathurst Harbour, 4 m, 16 Feb 1989, NMV J47323 (1 male, 5.5 mm) .

Description of female. Head with small dorsal elevation posteriorly, anterolateral lobes angular, small rostral point present; lateral margin of head and pereonite 1 incised. Pereonite 1 extended anterolaterally. Pereonites 2 and 3 without dorsal elevations, progressively wider, with small lateral extensions. Pereonite 4 about 8 times as long as pereonite 3, wider than previous pereonites, widest at midlength; with 2 anterior horn-like dorsal elevations, lateral margins extended and curved dorsally at midlength. Pereonites 5–7 progressively shorter posteriorly; without dorsal elevations. Pleon length greater than combined lengths of pereonites 5–7, without dorsal elevations, with small anterior lateral wings, apex rounded.

Eyes small and oval. Antenna 1 reaching to third peduncular article of antenna 2; aesthetascs present distally and laterally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 2 articles ending with claw, row of scales along full length.

Maxilla 1 mesial lobe with 3 plumose terminal setae; lateral lobe with 9 distal robust setae. Maxilla 2 mesial lobe with 22 plumose setae; middle lobe with 3 setae; lateral lobe with 3 setae. Maxillipedal endite with 13 mesial setae, 1 coupling hook; palp article 2 with mesial setal rows; articles 3 and 4 with mesial and lateral setal rows; article 5 with mesial and distal setae.

Pereopod 1 propodus as long as carpus; dactylus twice as long as wide, without unguis. Pereopods 2–3 dactylus present. Pereopod 4 dactylus absent. Pereopods 5–7 dactylus somewhat denticulate, with unguis and secondary unguis; secondary unguis half-length of primary unguis. Uropodal exopod with 2 setae of subequal length. Oostegite 4 with suture at midlength.

5.0– 6.6 mm.

Male. Head with a small dorsal elevation posteriorly, anterolateral lobes angular, small rostral point present; lateral margin of head and pereonite 1 incised. Pereonite 1 extended anterolaterally. Pereonites 2 and 3 of similar width; without dorsal elevations, small lateral extensions present. Pereonite 4 about nine times as long as pereonite 3, constricted for first third of length; with 2 anterior horn-like dorsal elevations, anterolateral margins not extended. Pereonites 5–7 progressively shorter posteriorly; without dorsal elevations. Pleon length greater than combined lengths of pereonites 5–7; without dorsal elevations, with small anterior lateral wings, apex rounded.

Antenna 1 reaching half way along third peduncular article of antenna 2; aesthetascs present distally and laterally on flagellum. Antenna 2 slender, more than half as long as body; flagellum of 3 articles ending with a claw, a row of scales full length.

Mouthparts, pereopods and uropods as for female.

Pleopod 1 exopod with a lateral notch and 2 plumose lateral setae of unequal length. Pleopod 2 appendix masculina with ridge on posterior face, curved, extending third length past the endopod, apex simple. Penial plate widened proximally, distally tapered, apex simple.

4.5–5.6 mm

Distribution. Australia: New South Wales, Victoria, Tasmania; subtidal to 9 m depth.

Etymology. “Coonabooloo ” is an Aboriginal word meaning two shoulders and refers to the extended lateral margins of pereonite 4 in the female of this species.

Remarks. This species possesses an incised dorsolateral groove at the fusion of the head and pereonite 1 as does Neastacilla deducta and N. monoseta . Females of N. coonabooloo are distinguished from these two species by the presence of extended lateral margins on pereonite 4 and two anterior horn-like elevations on pereonite 4. Males of N. coonabooloo possess smaller horn-like elevations. N. coonabooloo can be further differentiated from N. monoseta by possessing a pleon with small rounded lateral wings, as opposed to the large acute wings in N. monoseta . In the material examined here, the heights of the dorsal elevations on pereonite 4 vary from small bumps to spine like elevations.

Figures

Figure 1. Neastacilla coonabooloo sp. nov., male (NMV J47323): A, dorsal view; B, lateral view. Female holotype (NMV J1036): C, dorsal view; D, lateral view. Scale = 1.0 mm.

Figure 2. Neastacilla coonabooloo sp. nov., female holotype (NMV J1036): MX1, left MX2, left MD, left MXP, A1, A2, antenna 2. Male (NMV J47323): A1, A2. Scales: a (MXP, MX1, MX2, MD) = 0.2 mm; b (A1, A2) = 0.5 mm.

Figure 3. Neastacilla coonabooloo sp. nov., female holotype (NMV J1036): P1, P3, P4, P5, U; A, ventral view. Male (NMV J47323): Pe, PL1, PL2. Scales: a (P1, P3, P4) = 0.5 mm; b = (A) 1.0 mm; c (P5) = 0.5 mm; d (U, Pe, PL1, PL2) = 0.2 mm